Edgewise wound reactor coils and method of making the same



Oct. 6, 1959 G. THURK EDGEWISE WOUND REACTOR COILS AND METHOD OF MAKING THE SAME Original Filed March 14. 1952 .vn ll Inventor: W (7% United States Patent P EDGEWISE WOUND REACTOR COILS AND METHOD OF MAKING THE SAME Gerhard Thiirk, Berlin-Siemensstadt, Germany, assignor to Siemens-Schuckertwerke Aktiengesellschaft, Berlin- Siemensstadt, Germany, a corporation of Germany Continuation of application Serial No. 276,609, March 14, 1952. This application August 23, 1956, Serial No. 605,901.

Claims priority, application Germany April 13, 1951 '12 Claims. (Cl. 336-221) My invention relates to electromagnetic reactor coils and methods for making the same. In one of its particular but not exclusive aspects, the invention relates to saturable reactors of the type disclosed in the copending patent application of Paul Dufiing, Serial No. 225,229, filed May 8, 1951, U.S. Patent 2,765,448, issued October 2, 1956 entitled Saturable Switching Reactor, and assigned to the assignee of the present invention.

The present application is a continuation of my application, .Serial No. 276,609 filed on March 14, 1952, for Reactor Coils, subsequently abandoned.

The reactor constructed according to the Dufiing patent has an annular, wound magnetic core coaxially disposed within an annular housing formed of ceramic material and carrying a winding composed of individual U-shaped segments that are joined together at the outside of the annular assembly by straight intermediate bridge pieces or connecting members. With an uninsulated winding or a winding substantially free of organic insulation, such a reactor may be subjected to much higher operating temperatures and hence higher rated load currents than is permissible with reactors of conventional design and thus aifords a higher efficiency or a smaller and more compact design for any particular rating.

It is an object of my invention to further improve such reactors, in particularly structural features of the winding which simplify and greatly facilitate the manufacture and assembly of such reactors, without detriment to the above-mentioned operational advantages.

To this end, and in accordance with a feature of my invention, I provide a reactor, having an insulating housing of refractory inorganic material and an annular magnetizable core coaxially disposed therein, with a segmented reactor winding comprising a series of respective small and large winding segments alternating circumferentially around the housing periphery. One small winding segment and one adjacent large winding segment, when connected together, constitute two full turns of the complete winding, the small segments each providing less than one full turn and the large segments the balance of the two turns. Preferably, the small winding segments are generally U-shaped and extend substantially over only one-half turn of the winding, and the large winding segments are originally J-shaped, the longer leg being bent during assembly so that the segment extends completely around the core and constitutes somewhat more than one and one-quarter turns of the winding. The insulating housing may consist entirely of ceramic material. According to another feature of the invention, however, it is preferably composed of ceramic top and bottom end members of annular shape and hollow cylindrical or tubular sidewall members formed of metal, for instance, brass.

The foregoing and other additional objects and features of my invention will be apparent from the following 2,907,968 Patented Oct. 6, 1959 ICC description considered in conjunction with the accompanying drawing in which:

Fig. l is an axial cross sectional view of a reactor according to the invention showing one of the originally J-shaped winding segments hooked around-the core prior to being bent to extend around the core;

Fig. 2 is a perspective view showing an originally J- shaped segment bent to extend around the core, the bent segment being shown connected to two adjacent U-shaped segments and which form a part of the complete winding of the reactor according to Fig. 1, the core structure being omitted;

Fig. 3 is a fragmentary perspective view of the same reactor; and

Fig. 4 is a plan view of a modified form of U-shaped winding segment for use in such reactors;

The illustrated reactor comprises an annular housing designated generally as 3. The housing 3 includes two fiat, ring-shaped end members 12, 13 formed of ceramic material, such as porcelain or steatite, and two hollow cylindrical side wall members 14, 15 formed of metal, such as brass, or alternatively of ceramic material. Disposed in the annular space within the housing 3 is an annular magnetizable core 1 which, in the illustrated example, consists of three axially stacked core units. Each core unit is laminated and consists of a coiled strip or ribbon of magnetizable core material preferably having an approximately rectangular hysteresis characteristic. The core housing may also be composed of two ceramic half shells each of substantially U-shaped cross section as described in the above-mentioned copending Dufiing application.

However, the housing design according to the illustrated embodiment has the advantage that it can readily be adapted to accommodate any particular desired number of core units or cores of different axial dimensions merely by selecting or exchanging the tubular metal side walls for walls of the required axial length without requiring a change of the ceramic end members.

The left portion of Fig. 1 shows one of the small U- shaped winding segments or interconnecting means 17, which, in effect, forms slightly more than one half of a winding turn. Each segment 17 is essentially a U-shaped flat copper strip or stamping with bare, i.e. uninsulated, surfaces, and axially extending terminal ends. The right portion of Fig. 1 shows one of the J-shaped winding segments 18 prior to bending to form approximately one and one-quarter turns of the winding. This initially J- shaped winding segment likewise consists of a bare copper strip or stamping. As shown in full lines in Fig. l, the winding segment or element 18 is originally J-shaped and is hooked around the core with its lower closed end embracing the lower ceramic end member 13 and its longer leg 18a extending upwardly through the central window of the annular core and beyond the core structure. The shorter leg 18b extends parallel to the outer tubular metallic housing wall 14 and is maintained spaced outwardly away therefrom by the projecting outer edges of the upper and lower insulative end members 12 and 13. Longitudinally spaced notches 18c and 18d are formed in the longer leg 18a of the J-shaped winding segment 18, on the side thereof which is nearer to the central axis of the housing 3.

After it has first been hooked around the core housing 3 as shown in full lines in Fig. 1, the longer leg 18a of originally J-shaped winding segment or element 18 is bent in situ around the housing 3, so that it extends completely around the core as shown in dotted lines in Fig. 1. After bending, the free ends of segment 18 extend past each other at the outer side of housing 3 and both project axially beyond the end members 12 and 13. The confronting sides of the segment 18, after bending, are spaced apart circumferentially with respect to the housing 3.

The notch 18a is located in register with the inner edge of upper end member 12 and the notch 18d, which is originally above the notch 18c, is located inregister withthe outer edge of end member 12. The notches 2,907,968 V g V 18c and 1811 provide sections of; decreased moment of inertia about the bending axis thereby facilitating forming the two bends-of relatively short radius at the inner and outer edges of the upper end member 12. The other two' short radius bends which are located at the edges of lower end member 13. may be formed prior to hooking the J-shaped segment 18 around the housing 3; Because of its shape prior to bending,'the J-shaped seg- 311611818 maybe stamped from sheet copper and the bending operations, confined to the portions of reduced moment of inertia at the notches 18c and 18d. It will be appreciated that the formation of the bends at 18c and 18d'causes the bent winding segment 18 to be internally stressedso that it presses the end members 12 and 13 axially toward each other and holds the eler'nents 1, 14, 15, 12 and 13 of the core structure tightly assembled together under pressure. With a plurality of bent segments 18 arranged in a series around the housing 3, as shown, this axial pressure derived from the internal stressing of each bent segment is cumulative and the'reactor structure is therefore able to withstand severe mechanical stresses incident to transient overloads. When tubular side walls'14 and are used, as illustrated, and these side walls are formed of metal, the

ceramic end members 12 and 13 are provided with inwardly and outwardly radially projecting edge portions which maintain the winding segments spaced 'away from the tubular walls. This spacing, of course, must be sufii- 4 circuits between the winding turns. An insulating enamel coating as just-mentioned is shown at 17a in Fig. 4.

It may further bedesirable to give the U-shaped winding segments 17 an enlarged cross' section where they pass through the central window of theannular core thus reducing the overall resistance of the reactor winding. Such an enlarged cross section is also illustrated in Fig. 4 at the widened portion 17b of U-shaped segment 17. The enlargements have the further advantage of acting as cooling fins of large area. This is especially desirable when the reactor is tobe air cooled by means of a fan. Thejust-mention'ed cross sectional enlargement may also be continued nearly up to the terminal portions of the U-shaped winding segments 17.

For facilitating the installation of the reactor coil it may be desirable'to add ring-shaped discs of ceramic stantaneous value of an alternating current near its zero value as more fully explained in the above-mentioned copending application, but is of general applicability for any inductance coil with an annular magnetic core of laminated material, particularly Iclaim:

1. A reactor of the classdescribed, comprising: an

1 annular magnetic core; two axially spaced annular end nately in a series around the periphery of the housing 3 and are joined together at their axially extending projecting ends, for instance by soldering, brazing or welding, so as to form a continuous winding.

As apparent fromthe perspective illustration in Fig. 2, the upwardly extending terminal end at the right upper side of one U-shaped winding segment or interconnecting element 17 is welded to the adjacent terminal end of the next bent segment 18, these ends being in face to face contact. The lower end of bent segment 18 is similarly joined with another adjacent U-shaped winding segment 17. In this manner the entire winding is constituted by a series of such segments 17 and 18 serially conn'ected together. It will be recognized that the junction or welding terminal portions are alternately located at the top and bottom sides of the reactor assembly, two complete winding turns being disposed between each two adjacent upper junctions and between each two adjacent lower junctions. Consequently, a sufficient amount of working space is available for conveniently joining the winding segments 17 and 18 by welding or soldering.

The radially extending portions of winding segments 17 and 18 pass through and are received in radial slots or grooves 19 and 20, respectively, of the ceramic topand bottom end members 12, 13 of the housing 3 (see Figs. 1 and 3).

.In cases where additional protection against interturn short-circuits within the reactor is desired, the U-shaped winding segments 17 may be insulatedby a heat resistant coating, for instance of enamel, at least at those places where it passes axially through the central window of the core. Such insulation, located at members each formed of electrically insulative material, said end members being positioned adjacent to' respective axially spaced end surfaces of said core and projecting. radially both inwardly and outwardly beyond said core; a winding for the core, the winding in part comprising a circumferentially spaced series of separate independently internally stressed winding elements each extending around the minor circumference of said core, each of said elements having a length exceeding a single convolution therearound, said internal stressing causing each of said elements to press against both of said end members urging them axially toward each other to form a' firmly assembled reactor structure including said core, said end members and said series of elements; the winding further comprising means both electrically and mechanically interconnecting said elements to form a con- 7 tinuo us magnetizing winding for said core.

2. A reactor of the class described, comprisingz an annular magnetic core; two axially spaced annular end members each for-med of electrically insulative material,

I said end members being positioned adjacent to respective axially spaced end surfaces of said core and projecting radially both inwardly and outwardly beyond said core; a winding for the core, the Winding in part comprising a circumferentially spaced series of internally stressedv terconnecting the free ends of said elements to form a those places where adjacent winding turns lie closest to continuous magnetizing winding for said core.

3. A reactor according to claim 2, wherein said core is of generally rectangular transverse cross-sectional configuration thereby causing said elements to have bends of short radius at the corners of said core, outer edge portions of said flat strip material being cut away at said ben'ds for facilitating the'formation of said reactor.

of the coiled strip type.

7 4."A reactor accordingv to claim 12, in which said central portion of each U-shaped element is of increased width for decreasing the electrical resistance of said winding and simultaneously increasing the surface area thereof which is available for heat transfer purposes.

' 5. A reactor according to claim 12, in which said central portion of each U-shaped element is provided with an electrically insulative coating for preventing interturn short circuits.

- 6. An electromagnetic reactor comprising, in combination, a pair of coaxial flat annular electrically insulative end members, two concentric tubular members co-axial with said end members and extending axially therebetween, said end members and said tubular members constituting a housing defining a continuous annular space, an annular oore member disposed within said space, and an electromagnetic exciting winding generally toroidally surrounding said space exterior of said end members and said tubular'members, said electromagnetic winding in part comprising aseries of circumferentially spaced separately and individually internally stressed winding elements each comprising flat strip material facing said end members edgewise, the inner edges of all of said Winding elements cumulatively pressing said end members axially toward each other and toward said tubular members to confine said core within said space, said electromagnetic winding further comprising a series of interconnecting members connecting adjacent ones of said winding elements together, said interconnecting members being formed of fiat strip material, fiat surfaces of said interconnecting members being connected to abutting fiat surfaces of said segments.

7. An annular electromagnetic reactor comprising, in combination, a pair of coaxial annular electrically insulative end members, two concentric inner and outer tubular members coaxial with said end members and extending axially therebetween, said end members and said tubular members constituting a housing defining a continuous annular space, an annular magnetic core member disposed Within said space, and an electromagnetic exciting winding generally toroidally surrounding said space exteriorly of said end members and said tubular members, said electromagnetic winding in part comprising a series of circumferentially spaced winding elements each comprising fiat strip material facing said end members edgewise, and having end portions overlapping in extent and extending longitudinally, externally of the outer tubular member, the inner edges of said elements cumulatively pressing said end members axially toward each other and toward said tubular members, said electromagnetic winding further comprising a series of U- shaped interconnecting members connecting adjacent ones of said winding elements together, the central portions of the U-shaped members being within the inner tubular member, said interconnecting members being formed of fiat strip material, fiat terminal surfaces of said inter connecting members being connected to abutting flat surfaces of said end portions of the said winding elements.

8. An annular core electromagnetic reactor comprising, in combination, a pair of coaxial annular electrically insulative end plate members, two concentric inner and outer tubular members coaxial with said end plate members and extending axially therebetween, said end plate members and said tubular members constituting a housing defining a continuous annular space, an annular magnetic core member disposed within said space, and an electromagnetic exciting winding generally toroidally surrounding said space exteriorly of said end plate members and said tubular members, said electromagnetic winding in part comprising a series of circumferentially spaced winding elements each comprising fiat strip material facing said end plate members edgewise, and having a length exceeding a single convolution of said winding, the ends thereof extending longitudinally externally of the outer tubular member and having end portions extending axially beyond said insulative end plate members, the inner edges of all of said winding elements cumulatively pressing said end plate members axially toward each other and toward said tubular members to confine said core within said space, said electromagnetic winding further comprising a series of U-shaped interconnecting members connecting adjacent ones of said winding elements together, the central portions of the U-shaped members being within the inner tubular member, said interconnecting members being formed of flat strip material, fiat surfaces of said interconecting members being connected to abutting flat surfaces of said end portions of the winding elements.

9. An annular core electromagnetic reactor comprising, in combination, a pair of coaxial annular electrically insulative end plate members, two concentric inner and outer tubular members coaxial with said end plate members and extending axially therebetween, said end plate members and said tubular members constituting a housing defining a continuous annular space, an annular magnetic core member disposed within said space, and an electromagnetic exciting winding generally toroidally surrounding said space exteriorly of said end plate members and said tubular members, said electromagnetic winding in part comprising a series of oircumferentially spaced winding elements each comprising flat strip material facing said end plate members edgewise, and having a length exceeding a single convolution of said winding, the ends thereof extending longitudinally externally of the outer tubular member and having end portions extending axially beyond said insulative end plate members, the inner edges of all of said Winding elements cumulatively pressing said end plate members axially toward each other and toward said tubular members to confine said core within said space, said electromagnetic winding further comprising a series of U-shaped interconnecting members connecting adjacent ones of said winding elements together, the central portions of the U-shaped members being within the inner tubular member, said interconnecting members being formed of flat strip material, flat surfaces of said interconnecting members being connected to abutting flat surfaces of said end portions of the winding elements, the insulative end plate members having radial grooves, the said windin elements and the interconnecting members having radial-1y extending edge portions positioned in said grooves.

10. A reactor of the class described, comprising: an annular magnetic core; two axially spaced annular end members each formed of electrically insulative material, said end members being positioned adjacent to respective axially spaced end surfaces of said core and projecting radially both inwardly and outwardly beyond said core; an electromagnetic exciting winding toroidally surrounding said annular core exteriorly of said end members, said winding in part a circumferentially spaced series of separate independently internally stressed winding elements each extending around the minor circumference of said core, each of said elements having a length exceeding a single convolution therearound, said internal stressing causing each of said elements to press against both of said end members urging them axially toward each other to form a firmly assembled reactor structure including said core, said end members and said series of elements; said electromagnetic exciting winding further comprising means both electrically and mechanically interconnecting said elements to form a continuous magnetizing winding for said core, the means interconnecting said elements comprising unstressed bridging connectors extending within the central window of the magnetic core and connected to said elements externally of the said window, each of said connectors having a length less than a single convolution around the core.

11. The invention defined in claim 8, wherein said core is of rectangular cross-section, thereby causing said segments to have bends of short radius at the corners of the core, outerjedge portions of the flat strip material of the segments being cutaway at"sai-dbends to facilitate the formation of said reactor. g a 12. A reactor of the class, described, comprising: an annular magnetic core; two axially spaced annular end members each formed of electrically insulative material, said end members being positioned adjacent to respective axially spaced end surfaces of said core and projecting radiallyboth'inwardly and outwardly beyond said core; awinding for the core, the winding in part comprising a circumferential-1y spaced series of internally stressed winding elements each extending around the minor circumference of said core, each of said elements comprising flat strip material the. inner edge face of each of which embraces both of'the end members and each having a length exceedinga single convolution therearound, said internal stressing causing each of said elements to press its inner edges against both of said end members urging 1 them axially toward each other to form a firmly assembled reactor structure including said core, said end members and said series of elements; the winding further comprising means both electrically and mechanicallyinterconnecting the free ends; of said elements to form-a con tinuous magnetizing windi'ng for saidcore; said intercon;

necting means comprising'a series of urshaped-elem ents each formed of flat strip material and each comprising, a central portion which passes through the central window of said annular core, the free ends of said U-shaped elements being connected to contiguous free end portions of two difierent adjacent ones of said winding elements,

said interconnected free end portions extending axially beyond said end members at the outer side of said core.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS 505,251 Belgium Aug. 31, 1951 

